Retinoids (vitamin A) have recently attracted interest in what is seemingly a renaissance in the vision field in addition to their emergence in the areas of energy transduction (in the purple membrane, the proton pump of Halobacterium halobium), cancer prophylaxis, and acne therapy. The research involves the use of vinyl allene intermediates for synthesizing vitamin A as well as other target molecules. Besides being of interest as retinoid analogs in their own right, vinyl allenes can be thermally rearranged through a 1,5-sigmatropic shift of hydrogen to the 5, 7, 9, 11, 13-pentaene characteristic of the parent vitamin A system possessing an 11-cis geometry. We propose to continue studies in the following areas: (1) Application of the vinyl allene approach to the synthesis of various geometrically isomeric 11-cis-retinals as well as other variously substituted retinoids; (2) Examination of the Z yields E rearrangement of 11-Z-retinal and preparation of 11-Z-retinal with isotopic labels; (3) A scope study of the preparation and chemistry of vinyl allenes to further elaborate on the characteristics and limitations of the approach.